Problem 859. Get the elements of diagonal and antidiagonal for any m-by-n matrix

In the problem Problem 858. Permute diagonal and antidiagonal created by Jean-Marie SAINTHILLIER the test suite is only based on squared m-by-m matrix .

In this problem you must submit a solution which returns the diagonal and anti-diagonal elements without using the DIAG function for any m-by-n matrix

Example:

If the input is a matrix 4*3

x =  [ 0     0     0
       1    48    17
       0     2    99
       14    0    3]

we expect 2 output vectors:

dg_elements = [0 48 99] % diagonal elements

antidg_elements = [14 2 17 ] % anti-diagonal elements

Note : You do not have to permute anything. Just return the elements.